1. Field
The disclosure relates generally to a multi-version database and more specifically to compressing data records stored within the multi-version database.
2. Description of the Related Art
A multi-version database stores both current data records and historical data records in rows of a relational data table. The rows are typically annotated with timestamps representing the time period during which a row is valid or was valid. In a multi-version database system, new data records do not physically replace old ones. Instead, a new version of a data record is generated, which becomes visible to other transactions at commit time. Conceptually, many rows for a data record may exist, each row corresponding to a state of the multi-version database at some point in time.
However, in a multi-version database a challenge exists in managing a footprint of these multiple versions of a data record that are generated during updates. These multiple versions of the data record take up space on a magnetic hard disk drive. As a result, queries on data records stored on the magnetic hard disk drive are slowed down.